A Contraction Theory-Based Tracking Control Design With Friction Identification and Compensation

This article proposes a tracking controller for servomechanisms with continuous friction model. The parameters of this model are estimated through proposed two-step offline identification methodology that uses linear extended state observer (LESO) based on the integral position measurements, termed as ILESO. In first step, viscous and Coulomb coefficients by ordinary least squares method. second step employs these estimates to obtain initial guess nonlinear method identifies all nonlinearly parameterized Finally, backstepping is designed reference tracking, which online estimations servo position, velocity, system uncertainty. These provided modified ILESO, FILESO, has similar structure ILESO but incorporates identified into its dynamics. convergence stability established using contraction analysis. Experimental results show approach exhibits satisfactory performance.